Fuel Filler Pipe

The fuel filler pipe is of coaxial construction and consists of a central, fuel delivery tube inside of a molded, high-density polyethylene outer pipe. The space between the outer pipe and inner tube is used to carry fuel vapors and control their entry back into the tank during the refueling process. Refer to THEORY OF OPERATION - FUEL FILLING AND ORVR .

Fig 1: Fuel Filler Pipe

Courtesy of GENERAL MOTORS CORP.

There are two other components in this fuel filler pipe system (they are not serviceable):

• (1) Vapor Recirculation Valve - This is a spring-loaded, normally closed valve, located at the upper end of the filler pipe. The orifice in the valve meters fuel vapors generated during refueling back into the liquid fuel stream (dispensed from the nozzle) and back into the fuel tank. The main valve will only open at high tank pressures and allow vapor pressure to exit through the fuel cap.
  Fig 2: Vapor Recirculation Valve

  Courtesy of GENERAL MOTORS CORP.
• Fuel Fill Check Valve - Located on the end of the inner fuel delivery tube, this one-way check valve prevents liquid fuel from rushing back up the tube when the fuel delivery is stopped. It also prevents fuel tank vapors from traveling back up the inner filler tube.
  Fig 3: Fuel Fill Check Valve

  Courtesy of GENERAL MOTORS CORP.